Co-existence of depression and post-concussion syndrome one month after mild traumatic brain injury.

BACKGROUND: Previous studies suggest an association between Post-concussion syndrome (PCS) and depression, both highly prevalent after mTBI. OBJECTIVE: To assess the prevalence and risk-factors of depression among patients with PCS 1 month after mTBI. METHODS: We prospectively screened 372 mTBI patients admitted in two academic Emergency Departments between 2017 and 2019. One month after mTBI, we administered the Rivermead Post-concussion symptoms Questionnaire (RPQ) and the Patient Health Questionnaire (PHQ-9) questionnaires over the telephone. PCS and depression were defined by RPQ ≥ 12 and PHQ-9 ≥ 10. Multivariate multinomial regression identified baseline factors associated with PCS and depression. RESULTS: Two hundred and eight completed RPQ and PHQ-9. Forty-seven patients (22.5%) met criteria for PCS, among which 22 (46.8%) met criteria for depression (PCS+D+). Patients with PCS but without depression were less likely to present with an associated injury (Coefficient = -1.6, p = 0.047) and to report initial sadness (Coefficient = -2.5, p = 0.03). Initial sadness (Coefficient = -1.3, p = 0.047), associated injury (Coefficient = -1.9, p = 0.008), as well as initial nausea (Coefficient = -1.8, p = 0.002), and male sex (Coefficient = 1.8, p = 0.002), were associated with the absence of depression and PCS in comparison with PCS+D+ patients. CONCLUSION: Among patients with PCS 1 month after mTBI, those with depression are more likely to present with initial sadness and with an associated injury.

Neurofibromatosis type 1 mosaicism in patients with constitutional mismatch repair deficiency.

Differential diagnosis between constitutional mismatch repair deficiency (CMMRD) and neurofibromatosis type 1 (NF1) is crucial as treatment and surveillance differ. We report the case of a girl with a clinical diagnosis of sporadic NF1 who developed a glioblastoma. Immunohistochemistry for MMR proteins identified PMS2 loss in tumour and normal cells and WES showed the tumour had an ultra-hypermutated phenotype, supporting the diagnosis of CMMRD. Germline analyses identified two variants (one pathogenic variant and one classified as variant(s) of unknown significance) in the PMS2 gene and subsequent functional assays on blood lymphocytes confirmed the diagnosis of CMMRD. The large plexiform neurofibroma of the thigh and the freckling were however more compatible with NF1. Indeed, a NF1 PV (variant allele frequencies of 20%, 3% and 9% and in blood, skin and saliva samples, respectively) was identified confirming a mosaicism for NF1. Retrospective analysis of a French cohort identified NF1 mosaicism in blood DNA in 2 out of 22 patients with CMMRD, underlining the existence of early postzygotic PV of NF1 gene in patients with CMMRD whose tumours have been frequently reported to exhibit somatic NF1 mutations. It highlights the potential role of this pathway in the pathogenesis of CMMRD-associated gliomas and argues in favour of testing MEK inhibitors in this context.

A Minimal PBPK Model for Plasma and Cerebrospinal Fluid Pharmacokinetics of Trastuzumab after Intracerebroventricular Administration in Patients with HER2-Positive Brain Metastatic Localizations.

BACKGROUND: Dosing regimens of trastuzumab administered by intracerebroventricular (icv) route to patients with HER2-positive brain localizations remain empirical. The objectives of this study were to describe pharmacokinetics (PK) of trastuzumab in human plasma and cerebrospinal fluid (CSF) after simultaneous icv and intravenous (iv) administration using a minimal physiologically-based pharmacokinetic model (mPBPK) and to perform simulations of alternative dosing regimens to achieve therapeutic concentrations in CSF. METHODS: Plasma and CSF PK data were collected in two patients with HER2-positive brain localizations. A mPBPK model for mAbs consisting of four compartments (tight and leaky tissues, plasma and lymph) was enriched by an additional compartment for ventricular CSF. The comparison between observed and model-predicted concentrations was evaluated using prediction error (PE). RESULTS: The developed mPBPK model described plasma and CSF trastuzumab concentrations reasonably well with mean PE for plasma and CSF data of 41.8% [interquartile range, IQR = -9.48; 40.6] and 18.3% [-36.7; 60.6], respectively, for patient 1 and 11.4% [-10.8; 28.7] and 22.5% [-27.7; 77.9], respectively, for patient 2. Trastuzumab showed fast clearance from CSF to plasma with Cmin,ss of 0.56 and 0.85 mg/L for 100 and 150 mg q1wk, respectively. Repeated dosing of 100 and 150 mg q3day resulted in Cmin,ss of 10.3 and 15.4 mg/L, respectively. Trastuzumab CSF target concentrations are achieved rapidly and maintained above 60 mg/L from 7 days after a continuous perfusion at 1.0 mg/h. CONCLUSION: Continuous icv infusion of trastuzumab at 1.0 mg/h could be an alternative dosing regimen to rapidly achieve intraventricular CSF therapeutic concentrations.

Comparing the Effect of Implanted Peroneal Nerve Stimulation and Ankle-Foot Orthosis on Gait Kinematics in Chronic Hemiparesis: A Randomized Controlled Trial.

OBJECTIVE: Impaired ankle dorsiflexion in hemiparesis may be treated with ankle-foot orthosis or functional electrical stimulation. Semi-implanted selective functional electrical stimulation uses independent stimulations of deep and superficial peroneal nerves. The aim of this study was to compare gait kinematics using ankle-foot orthosis or semi-implanted selective functional electrical stimulation over 6 months in hemiparesis. METHODS: Subjects with chronic hemiparesis, randomized into ankle-foot orthosis or semi-implanted selective functional electrical stimulation groups, underwent comfortable gait analysis without and with device OFF and ON, before, and 3 and 6 months after treatment onset. The effects of condition, visit and group on gait kinematics (analysis of variance; ANOVA) were analysed. RESULTS: A total of 27 subjects were included (ankle-foot orthosis, n = 13; semi-implanted selective functional electrical stimulation, n = 14). The only between-group difference in changes from OFF to ON conditions was a deteriorated ankle dorsiflexion speed with ankle-foot orthosis at month 6 (condition*group, p = 0.04; ankle-foot orthosis, -60%, p = 0.02; semi-implanted selective functional electrical stimulation, non significant). Both groups pooled, from OFF to ON gait speed (+ 0.07 m/s; + 10%), cadence (+ 4%), step length (+ 6%) and peak ankle dorsiflexion (+ 6°) increased, and peak ankle inversion (-5°) and peak knee flexion (-2°) decreased (p < 0.001); finally, peak knee flexion in the OFF condition increased (+ 2°, p = 0.03). CONCLUSION: Semi-implanted selective functional electrical stimulation and ankle-foot orthosis similarly impacted gait kinematics in chronic hemiparesis after 6 months of use. Ankle dorsiflexion speed in swing deteriorated markedly with ankle-foot orthosis.

Blood Biomarkers for Return to Play after Concussion in Professional Rugby Players.

We prospectively evaluated a panel of seven blood biomarkers (S100 calcium-binding protein B [S100B], neuron specific enolase [NSE], spectrin breakdown products [SBDP], ubiquitin C-terminal hydrolase L1 [UCHL1], glial fibrillary acidic protein [GFAP], neurofilament light chain [NFL], and tubulin-associated unit [Tau]) for sport-related concussion (SRC) in a large multi-centric cohort of 496 professional rugby players from 14 French elite teams. Players were sampled twice during the season (beginning and end) away from any sport practice. From these two baseline samples, we evaluated the intra-individual variability to establish the effect of rugby on blood biomarkers over a season. Only S100B and GFAP remained stable over the course of a season. During the period of the study, a total of 45 SRC cases was reported for 42 players. In 45 SRCs, the head injury assessment (HIA) process was performed and blood collection was realized 36 h after the concussion (HIA-3 stage). For each biomarker, raw concentrations measured 36 h after SRC were not significantly different between players with a non-resolutive SRC (n = 28) and those with a resolutive SRC (n = 17; p between 0.06 and 0.92). In a second step, blood concentrations measured 36 h after SRC were expressed according to the basal concentrations as an individual percentage change (PCH36[%]), calculated as follows: PCH36 = 100 × (([Biomarker]36h - [Biomarker]basal)/[Biomarker]basal). S100B and NFL concentrations expressed as PCH36[%] were significantly different between non-resolutive and resolutive SRCs (p = 0.006 and 0.01 respectively), with a positive delta found in non-resolutive SRCs. Among the two biomarkers, it is important to note that only the S100B protein was stable during the season. In the context of our study, during HIA-3 assessment, S100B seems to perform better than NSE, SBDP, UCHL1, GFAP, NFL, and Tau as biomarker for SRC. From a clinical standpoint, the S100B modification over baseline may be valuable, at 36 h after concussion to distinguish non-resolutive SRC from resolutive SRC.

How is Video Efficient to Diagnose Sport-Related Concussion? A Cross-Sectional Study in the French TOP14 Rugby Championship.

OBJECTIVE: To describe the frequency of clinical signs and the accuracy of video diagnosis of sport-related concussion. DESIGN: An observational cross-sectional study. SETTING AND PARTICIPANTS: Videos from a database of all suspected sport-related concussion in TOP14 matches (French professional male rugby Championship) were used, from 2012 to 2015 seasons. The videos were analyzed by 4 observers, blinded to the concussion diagnosis, after a training phase, and an inter-rater reliability analysis. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Video analysis for clinical signs and presumed diagnosis of sport-related concussion. The observer's diagnosis was compared with the team physicians' diagnosis. RESULTS: Four hundred seventeen videos were analyzed with 142 concussed players. Sport-related concussions happened mostly from an impact to the head (seen by the observers in 98.4%), against an opponent (73.2%), and during a tackle (74.6%). Video signs were observable in 98.6% for suspected loss of consciousness, tonic posturing (95%), ataxia (77.2%), dazed look (35.7%), abnormal behavior (18.2%), and seizures (96.2%). Ataxia was seen in 77.7% of concussed players, suspected loss of consciousness in 61.4%, dazed look in 63.2%, abnormal behavior in 55%, and tonic posturing in 7.1%. The observers diagnosed 79.8% of concussions. CONCLUSIONS: We described the frequency of video clinical signs of sport-related concussion, with a good accuracy of the blinded observers for the diagnosis. This emphasizes the importance of pitch-side video analysis as an extra tool for sport-related concussion diagnosis.

Incidence and Risk Factors in Concussion Events: A 5-Season Study in the French Top 14 Rugby Union Championship.

BACKGROUND: Concussions are a source of major concern in rugby, and a limited number of studies have attempted to identify risk factors for these injuries. PURPOSE: To investigate the incidence of match concussion and associated risk factors, including individual workload, anthropometric variables, playing position, and season phase, in elite rugby union players. STUDY DESIGN: Case-control study; Level of evidence 3. METHODS: All concussions and explanatory variables were collected for every match over 5 consecutive seasons (2014-2018) in 1334 professional players participating in the French Top 14 championship. Concussion risk was estimated using mixed effects Poisson regression. RESULTS: Mean match concussion incidence equated to 10.4 (95% CI, 9.3-11.5) concussions for 1000 hours of game exposure. A peak was reached in the 2016-2017 season (13.7; 95% CI, 11.0-16.5). A greater risk was observed in the playoffs as compared with the first phase of the season (incidence rate ratio, 3.96; 95% CI, 2.10-7.35). In comparison with other positions, half-backs incurred the highest rate of concussion events (incidence, 16.1; 95% CI, 11.8-20.3). Irrespective of playing position, those with greater height and lower body mass reported a higher risk of concussions (P = .02), especially during tackling actions for lighter players (P = .01) and during other match events for taller players (P = .03). When adjusted for season phase, players who had accumulated a higher amount of playing time since the beginning of the season demonstrated a lower risk of concussion (P = .005). CONCLUSION: Inter- and intraseasonal variations in concussion rates were observed. Within positional groups, lighter and taller players were more at risk, with the highest incidence generally observed in half-backs. Workload was measured by the number of matches played before a concussion event, and it appeared to have a protective rather than deleterious effect on concussion risk.

A governmental program to encourage medical students to deliver primary prevention: experiment and evaluation in a French faculty of medicine.

BACKGROUND: A public health student service was set up by the French government in 2018 with the aim of increasing awareness of primary health promotion among the 47,000 students of medicine and other health professions. It is an annual program involving community-based actions on nutrition, physical activity, addiction or sexuality. Our objective was to evaluate its implementation at local level and the different experiences of the stakeholders. METHODS: A quasi-experimental study using process evaluation was performed in a Faculty of Medicine in Paris. Quantitative and qualitative data were collected from medical students who carried out preventive health actions, in the institutions in which the actions took place and from a subsample of beneficiaries. RESULTS: One hundred and eight actions were carried out by 341 students in 23 educational or social institutions, mostly high schools (n = 12, 52%). Two thirds of the students did not feel sufficiently prepared to deliver preventive health interventions (65.7%, 224/341); however the beneficiaries found that the interventions were good (278/280, 99,2%). Nineteen (83%) of the host institutions agreed to welcome health service students again, of which 9 required some modifications. For students, the reporting of a satisfactory health service experience was associated with the reporting of skills or knowledge acquisition (p < 0.01). Delivering actions in high schools and to a medium-sized number of beneficiaries per week was associated with students' satisfaction. No effect of gender or theme of prevention was observed. For 248/341 (72.7%) students, the public health service program prompts them to address prevention issues in the future. CONCLUSION: The public health service undertaken by medical students through the program is a feasible and acceptable means of delivering preventive actions. Reinforcement of training and closer interaction with the host institutions would improve results.

What Is the Impact of Physical Effort on the Diagnosis of Concussion?

OBJECTIVE: Sport-related concussion commonly occurs in contact sports such as rugby. To date, diagnosis is based on the realization of clinical tests conducted pitch-side. Yet, the potential effect of prior physical effort on the results of these tests remains poorly understood. The purpose of this study was to determine whether preceding physical effort can influence the outcome of concussion assessments. DESIGN: Prospective observational study. SETTING: University Medicine Center. PATIENTS: A cohort of 40 subjects (20 rugby players and 20 athletes from a range of sports). INTERVENTION: A concussion assessment was performed immediately after physical activity. After a period of 6 months and under the same experimental conditions, the same cohort performed the same tests in resting conditions. MAIN OUTCOME MEASURES: Results of concussion tests. RESULTS: In both cohorts, the comparison for postexercise and rest assessments demonstrated a most likely moderate-to-very large increase in the number of symptoms, severity of symptoms, and balance error scoring system score. In the rugby cohort, scores for concentration, delayed memory and standardized assessment of concussion (SAC), likely-to-most likely decreased following completion of physical activity compared with baseline values. The between-cohort comparison reported a most likely greater impact after exercise in the rugby players for delayed recall (0.73 ± 0.61) and SAC score (0.75 ± 0.41). CONCLUSIONS: Physical activity altered the results of concussion diagnostic tests in athletes from a range of sports and notably in rugby players. Therefore, physical efforts before the concussion incident should be accounted for during pitch-side assessments and particularly during rugby competition and training.

Surface reconstruction from routine CT-scan shows large anatomical variations of falx cerebri and tentorium cerebelli.

BACKGROUND: Finite element modeling of the human head offers an alternative to experimental methods in understanding the biomechanical response of the head in trauma brain injuries. Falx, tentorium, and their notches are important structures surrounding the brain, and data about their anatomical variations are sparse. OBJECTIVE: To describe and quantify anatomical variations of falx cerebri, tentorium cerebelli, and their notches. METHODS: 3D reconstruction of falx and tentorium was performed by points identification on 40 brain CT-scans in a tailored Matlab program. A scatter plot was obtained for each subject, and 8 anatomical landmarks were selected. A reference frame was defined to determine the coordinates of landmarks. Segments and areas were computed. A reproducibility study was done. RESULTS: The height of falx was 34.9 ± 3.9 mm and its surface area 56.5 ± 7.7 cm2. The width of tentorium was 99.64 ± 4.79 mm and its surface area 57.6 ± 5.8 cm2. The mean length, height, and surface area of falx notch were respectively 96.9 ± 8 mm, 41.8 ± 5.9 mm, and 28.8 ± 5.8 cm2 (range 15.8-40.5 cm2). The anterior and maximal widths of tentorial notch were 25.5 ± 3.5 mm and 30.9 ± 2.5 mm; its length 54.9 ± 5.2 mm and its surface area 13.26 ± 1.6 cm2. The length of falx notch correlated with the length of tentorial notch (r = 0.62, P < 0.05). CONCLUSION: We observe large anatomical variations of falx, tentorium, and notches, crucial to better understand the biomechanics of brain injury, in personalized finite element models.

Long-term consequences of recurrent sports concussion.

BACKGROUND: Recurrent concussions are suspected to promote the development of long-term neurological disorders. The study was designed to assess the prevalence of major depressive disorder, mild cognitive disorders and headache in a population of retired high-level sportsmen and rugby players and to study the link between scores evaluating these disorders and the number of reported concussions (RCs). METHODS: A total of 239 retired rugby players (RRPs) and 138 other retired sportsmen (ORSs) who had reached the French national or international championship level between 1985 and 1990 filled in a self-administered questionnaire describing their sociodemographic data, comorbidities and reported history of RC. A phone interview was then conducted using validated questionnaires for the detection of major depressive disorder (PHQ-9), mild cognitive disorders (F-TICS-m) and headache (HIT-6). RESULTS: RRPs reported a higher number of RCs than ORSs (p < 0.001). A higher rate of major depressive disorder (PHQ-9 score >9) was observed among RRPs compared to ORSs (9% versus 6%) (p = 0.04), and the PHQ-9 score increased with the number of RCs regardless of the type of sport (p = 0.026). A higher rate of mild cognitive disorders (TICS-m score ≤30) was observed in RRPs compared to ORSs (57% versus 40%, p = 0.005), but no association was found with the number of RC. The HIT-6 score increased with the number of RCs (p = 0.019) CONCLUSIONS: More than 20 years after the end of their career, RRPs present higher rates of depression and lower F-TICS-m scores in favor of mild cognitive impairment compared with ORSs. PHQ-9 and HIT-6 scores were significantly associated with the number of RCs.

Volumetric relief map for intracranial cerebrospinal fluid distribution analysis.

Cerebrospinal fluid imaging plays a significant role in the clinical diagnosis of brain disorders, such as hydrocephalus and Alzheimer's disease. While three-dimensional images of cerebrospinal fluid are very detailed, the complex structures they contain can be time-consuming and laborious to interpret. This paper presents a simple technique that represents the intracranial cerebrospinal fluid distribution as a two-dimensional image in such a way that the total fluid volume is preserved. We call this a volumetric relief map, and show its effectiveness in a characterization and analysis of fluid distributions and networks in hydrocephalus patients and healthy adults.

The prevalence of IgG4-positive plasma cells in hypophysitis: a possible relationship to IgG4-related disease.

AIMS: Hypophysitis is a rare chronic inflammation of the pituitary gland corresponding currently to six histopathological subtypes. Among them, immunoglobulin- G4-related hypophysitis was recently added in this classification. The aim of this study was to perform a retrospective histopathological and immunohistochemical analysis to evaluate the prevalence of IgG4-related hypophysitis and review reported cases. METHODS: All samples of hypophysitis from Lariboisiere hospital were reviewed by two pathologists to assess their subtypes. An immunohistochemistry against IgG4 and IgG was performed. Slides were numerized, and IgG4-positive plasma cells and IgG plasma cells were counted in three high-power fields to evaluate the ratio. RESULTS: Eight cases were included: 5 lymphocytic hypophysitis, 1 granulomatous subtype, and 2 IgG4-related hypophysitis, affecting two young women without other coaffected organ. CONCLUSION: Our results show that IgG4-related hypophysitis is not an exceptional entity. Storiform fibrosis and obliterative phlebitis, histopathological characteristics of IgG4-related disease in other organs, are lacking in pituitary lesions. This study proves the interest of immunohistochemistry for diagnosis of IgG4-related hypophysitis. Due to the sensibility of IgG4-disease to steroids in other organs, this finding could be of clinical relevance.

The International Rugby Board (IRB) Pitch Side Concussion Assessment trial: a pilot test accuracy study.

BACKGROUND: 'On the field and on the run' assessments of head impact events in professional rugby have resulted in a high proportion of players subsequently diagnosed with confirmed concussion not leaving the field of play at the time of injury. The International Rugby Board (IRB) consequently developed a process to support team doctors in the recognition and management of players at risk of concussion, including development of a multimodal assessment instrument-the Pitch Side Concussion Assessment (PSCA) tool. METHODS: This was a pilot cohort study designed to determine the feasibility of assessing the accuracy of the IRB PSCA tool in elite male rugby. The study population comprised consecutive players identified with a head impact event with the potential to result in concussion during eight international/national competitions. Players were assessed off field by match-day or team doctors, following a temporary substitution. The accuracy of the PSCA tool was measured against a reference standard of postmatch confirmed concussion, based on clinical judgement aided by an established concussion support instrument. RESULTS: A total of 165 head injury events with the potential to cause concussion were included in the study. The PSCA tool demonstrated a sensitivity of 84.6% (95% CI 73.5% to 92.4%) and a specificity of 74% (95% CI 64.3% to 82.3%) to identify players subsequently diagnosed with confirmed concussion. The negative predictive value was 88.1% (95% CI 79.2% to 94.1%); the positive predictive value was 67.9% (95% CI 56.6% to 77.8%). There were no major barriers identified that would prevent the evaluation of the PSCA process or tool in a future large-scale study. CONCLUSIONS: This pilot study has provided the first preliminary estimates for the performance of the PSCA tool, suggesting a potentially favourable balance between positive and negative predictive values. The study has also offered a strong basis to conduct a further larger trial, providing information for sample size calculations and highlighting areas for methodological development.

3D mapping of cerebrospinal fluid local volume changes in patients with hydrocephalus treated by surgery: preliminary study.

OBJECTIVE: To develop automated deformation modelling for the assessment of cerebrospinal fluid (CSF) local volume changes in patients with hydrocephalus treated by surgery. METHODS: Ventricular and subarachnoid CSF volume changes were mapped by calculating the Jacobian determinant of the deformation fields obtained after non-linear registration of pre- and postoperative images. A total of 31 consecutive patients, 15 with communicating hydrocephalus (CH) and 16 with non-communicating hydrocephalus (NCH), were investigated before and after surgery using a 3D SPACE (sampling perfection with application optimised contrast using different flip-angle evolution) sequence. Two readers assessed CSF volume changes using 3D colour-encoded maps. The Evans index and postoperative volume changes of the lateral ventricles and sylvian fissures were quantified and statistically compared. RESULTS: Before surgery, sylvian fissure and brain ventricle volume differed significantly between CH and NCH (P = 0.001 and P = 0.025, respectively). After surgery, 3D colour-encoded maps allowed for the visual recognition of the CSF volume changes in all patients. The amounts of ventricle volume loss of CH and NCH patients were not significantly different (P = 0.30), whereas readjustment of the sylvian fissure volume was conflicting in CH and NCH patients (P < 0.001). The Evans index correlated with ventricle volume in NCH patients. CONCLUSION: 3D mapping of CSF volume changes is feasible providing a quantitative follow-up of patients with hydrocephalus. KEY POINTS: • MRI can provide helpful information about cerebrospinal fluid volumes. • 3D CSF mapping allows quantitative follow-up in communicating and non-communicating hydrocephalus. • Following intervention, fissures and cisterns readjust in both forms of hydrocephalus. • These findings support the hypothesis of suprasylvian block in communicating hydrocephalus. • 3D mapping may improve shunt dysfunction detection and guide valve pressure settings.

Neuromechanical assessment of lidocaine test block in spastic lower limbs.

The objective of this study was to quantify in spastic lower limbs the changes in reflex EMGs and in ankle stiffness after a lidocaine block of the soleus nerve to better understand physiological effects of lidocaine. Twenty patients were prospectively included and assessed before and after lidocaine block of the soleus nerve. We studied clinical and neuromechanical parameters of the triceps surae, including quantification of the maximum Hoffmann's reflex (Hmax) and tendinous reflex (T) normalized to the maximum direct motor response (Mmax), and passive ankle stiffness assessed by sinusoidal length perturbations. All patients whatever the aetiology of spasticity were improved in clinical parameters of spasticity after the block (62% reduction of the Ashworth score, 85% reduction of stretch reflex scores, increased score on the Physicians' Rating Scale). All patients presented a reduction of the Hmax-Mmax ratio (mean reduction of 67%) and the T-Mmax ratio (82%). Ankle stiffness was decreased by an average of 23%. Measured stiffness was correlated with the Ashworth score and the T-Mmax ratio. Relatively greater change in the T reflex than in the H reflex suggests that lidocaine block reduces hyperreflexia not only by interfering with generation of afferent volleys in the injected nerve, but also probably by altering generation of the volleys at the level of muscle spindles in the affected spastic muscles, presumably by blocking the transmission along gamma-efferent fibers.

Time course of the soleus M response and H reflex after lidocaine tibial nerve block in the rat.

AIMS: In spastic subjects, lidocaine is often used to induce a block predictive of the result provided by subsequent surgery. Lidocaine has been demonstrated to inhibit the Hoffmann (H) reflex to a greater extent than the direct motor (M) response induced by electrical stimulation, but the timecourse of these responses has not been investigated. METHODS: An animal (rat) model of the effects of lidocaine on M and H responses was therefore developed to assess this time course. M and H responses were recorded in 18 adult rats before and after application of lidocaine to the sciatic nerve. RESULTS: Two to five minutes after lidocaine injection, M responses were markedly reduced (mean reduction of 44%) and H reflexes were completely abolished. Changes were observed more rapidly for the H reflex. The effects of lidocaine then persisted for 100 minutes. The effect of lidocaine was therefore more prolonged on the H reflex than on the M response. CONCLUSION: This study confirms that lidocaine blocks not only alpha motoneurons but also Ia afferent fibres responsible for the H reflex. The authors describe, for the first time, the detailed time course of the effect of lidocaine on direct or reflex activation of motoneurons in the rat.

Intraventricular and skull base neuroendoscopy in 2012: a global survey of usage patterns and the role of intraoperative neuronavigation.

BACKGROUND: During the past decade, endoscopic intraventricular and skull base operations have become widely used for a variety of evolving indications. A global survey of practicing endoscopic neurosurgeons was performed to characterize patterns of usage regarding endoscopy equipment, instrumentation, and the indications for using image-guided surgery systems (IGSs). METHODS: An online survey consisting of 8 questions was completed by 235 neurosurgeons with endoscopic surgical experience. Responses were entered into a database and subsequently analyzed. RESULTS: The median number of operations performed per year by intraventricular and skull base endoscopic surgeons was 27 and 25, respectively. Data regarding endoscopic equipment brand, diameter, and length are presented. The most commonly reported indications for IGSs during intraventricular endoscopic surgery were tumor biopsy/resection, intraventricular cyst fenestration, septostomy/pellucidotomy, endoscopic third ventriculostomy, and aqueductal stent placement. Intraventricular surgeons reported using IGSs for all cases in 16.6% and never in 24.4%. Overall, endoscopic skull base surgeons reported using IGSs for all cases in 23.9% and never in 18.9%. The most commonly reported indications for IGSs during endoscopic skull base operations were complex sinus/skull base anatomy, extended approaches, and reoperation. CONCLUSIONS: Many variations and permutations for performing intraventricular and skull base endoscopic surgery exist worldwide. Much can be learned by studying the patterns and indications for using various types of equipment and operative adjuncts such as IGSs.